Post-mortem study of brains of people aged 80 and over with exceptional memory reveals much larger neurons in the region of the brain responsible for memory, providing insight into how and why some resist to Alzheimer’s disease.
- Alzheimer’s disease is a neurodegenerative disease characterized by a progressive loss of memory and certain intellectual functions leading to repercussions in the activities of daily living.
- 55.2 million people are affected by Alzheimer’s disease or a related disease in the world according to the WHO.
Old age does not always rhyme with memory loss, on the contrary! Indeed, some people aged 80 or over retain an exceptional ability to remember information… It may even be greater than that of young people aged 20 to 30.
Researchers from Northwestern Medicine in the United States have looked into this question and found that these people have “super neurons” in the area of the brain responsible for memory. Called the entorhinal cortex, this area is one of the first places targeted by Alzheimer’s disease.
These “super neurons” are present from birth in the brain
According to the study published in The Journal of Neurosciencethese “super neurons“are taller, healthier, and are relatively free of tau tangles, a hallmark of Alzheimer’s disease.
These neurons are a true biological signature conclude the authors:
“The remarkable observation that these people exhibited larger neurons than their peers when they were younger may imply that the large cells were present from birth and sustained structurally throughout their lives.said lead author Tamar Gefen, assistant professor of psychiatry and behavioral sciences at Northwestern University’s Feinberg School of Medicine.
To carry out their work, the scientists examined the post-mortem brains of thirteen people aged 80 or over (six had exceptional memory and seven were average cognitively), six young people and five people with the first stages of Alzheimer’s disease.
They then measured the size of neurons in layer II of the entorhinal cortex. This layer in particular receives information from other memory centers and is a very specific and crucial hub of memory circuitry in the brain. They also measured and compared the presence of tau tangles in these neurons.
Tau tangles are a biomarker of Alzheimer’s
Their results suggest that a neuron spared from forming Tau tangles can maintain its structural integrity, i.e. remain healthy and large. The reverse also appears to be true: Tau tangles can cause neurons to shrink, which appears to be a hallmark marker of Alzheimer’s disease where memory abilities in old age are poor.
“Identifying this contributing factor (and all contributing factors) is crucial for early identification of Alzheimer’s disease, monitoring its course, and guiding treatment.“concluded Tamar Gefen.
